1. Field of the Invention
This invention relates to a telephoto lens.
2. Description of the Prior Art
In telephoto lenses, it is generally desirable that the distance from the foremost surface of the lens to the focal plane thereof (namely, the total length of the lens) be small, but there is a limit to the reduction in such distance in order to well balance various aberrations in a practicable range. Further, it has been unavoidable that as the brightness of the lens is higher, the ratio of the total length to the focal length, the so-called telephoto ratio, becomes greater.
Accordingly, in the known typical telephoto lenses of five-group construction like the lens of the present invention, the F-numbers thereof has been F4 or F5.6 at best.